Final Exam Flashcards
who is Robert Hooke?
-invented first microscope
-analyzed cork bark and saw cells
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who is Anthony Van Leeuwenhock
-wealthy merchant who worked with glass
-created high quality lenses with which 300x magnification was possible
-was protists from algae
-saw bacteria from tooth plaque
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what happened in 1830?
-compound microscope was invented
-improved magnification and resolution
who is Robert Brown?
-botanist
-saw that every plant cel contained a round structure (nucleus)
who is Matthias Scheilden?
-botanist
-all plant tissue is composed of cells
-embryonic plant arose from single cell
who is Theodor Schwann?
-zoologist
-similar observations as brown and scheilden but in animal cells
-formulated the cell theory
what is the cell theory?
-all organisms consist of one or more cells
-the cell is the basic unit of structure for all organisms
-all cells arise only from pre-existing cells
generally explain the secretory pathway
Rough ER
-synthesis of proteins
Golgi
-collection, packaging, distribution of proteins
Lysosomes
-“cell stomach”
-can fuse with vesicles
-material brought into cell by phagocytosis
what is the endosymbiont theory?
-mitochondria and chloroplasts were once prokaryotes that were engulfed by larger cells
-have double membrane and their own genome
-have their own ribosomes
-genetically similar to parent bacteria rather than eukaryotic cell
what is a scientific fact?
-based on observations and experiments
-attempt to explain our current, best explanation
-valid until replaced by better facts with careful observations and experiments
what is the scientific method
-make observations
-make a hypothesis based on observations
-make predictions based on the hypothesis
-further testing and observations of hypothesis adds strength to it
-interpret results to see if hypothesis is true
what is a theory?
-Once the hypothesis has been greatly tested and there is enough evidence to support it strongly
-Once it is accepted by most scientists the hypothesis is now a theory
-E.g. Germ theory, evolution, cell theory -A law is more solid than a theory (there is no doubt that it is true)
-E.g. Law of gravity, thermodynamics, behaviour of gases
-Biologists are conservative in using the term “law”
which strand of DNA is transcribed
the template strand, read in a 3’ to 5’ direction
how are the bases bonded together?
-phosphodiester bonds form in each strand (nucleoside triphosphate loses 2 phosphates and bonds to OH link)
-hydrogen bonds between the strands at each base
how is DNA transcribed?
-RNA polymerase
-binds to DNA at promotor sequence and unwinds it (sigma factor recognizes sequence)
-sigma factor finds the -10 and -35 boxes and binds to them to properly orient the RNA polymerase holoenzyme
-sigma factor is released after RNA synthesis begins
-ribonucleoside triphosphates come in through the uptake channel and match with the template strand
-then mRNA leaves and the DNA is wound back up with its other strand
how is transcription terminated in bacteria?
-polymerase termination signal
-this codes for RNA that folds back up on itself (hairpin loop)
-this disrupts the transcription complex and polymerase releases RNA transcript and DNA template
how is transcription different in eukaryotes?
-DNA is tightly packed around histones
-3 types of RNA polymerase
-promotors are more complex
-RNApol II recognizes many promotors including the TATA box which is 30 bp upstream
-general transcription factors must assemble at promotor along with RNApol
-mRNA is further processed before leaving the nucleus
initiation of transcription in eukaryotes
-TATA box recognized by TATA binding protein (TBP)
-TBP is a subunit of a transcription factor (TFIID)
-TFIID binding allows other transcription factors to bind and form the transcription initiation complex
-TFIIH pries the double helix apart at the transcription start point
modifications after transcription
-modifications carried out by enzymes that ride on RNApol II
-nRNA 5’ G cap
-poly-A tail on 3’ end
-introns are taken out (splicing) (occirs while still being transcribed)
how does splicing occur?
-intron sequence forms a loop by taking a point in the intron and attaching it to the 5’ end
-cut end on 5’ end forms a covalent bond with the ribose sugar group on 3’ end
-lariat (loop) is degraded
-carried out by spliceosomes
what are spliceosomes
-consists of 5 small nuclear ribonucleic particles (snRNPs)
-considered ribozyme
what are the advantages of RNA splicing?
-can create different proteins from the same gene/ primary transcript
what are the disadvantages of RNA splicing?
-more steps
-more work
-more opportunity for error
-mutations of splice can result in: loss of exons, inclusion of introns, and shift in location of splice
what happens after the modifications?
-cap and poly-A tail are marked by proteins
-group of proteins (exon junction complex or EJC) binds to spliced mRNA
-mRNA transported out of nuclear pore into cytoplasm
